Research on the post-earthquake dynamic response of CRTS III slab ballastless track-bridge system in settlement risk area

Current research on high-speed railway track-bridge system primarily focuses on single load conditions of either earthquake or pier settlement, neglecting the coupling correlation between them and severely underestimating the dynamic response of track-bridge system. To address this limitation, a damage evolution model for CRTS III slab ballastless track and an analysis and design method for track residual irregularity characteristics was proposed. First, a simplified track modeling design was adopted to significantly reduce the model degrees of freedom, achieving approximately 40% improvement in computational efficiency compared to traditional finite element models. An adaptive mesh evolution mechanism was introduced to realize local mesh refinement in damaged regions, enhancing the model solution accuracy. The reliability of the damage evolution model was validated through shaking table tests and numerical mapping models. Subsequently, based on this model, the track interlayer damage evolution mechanism and law were revealed, the track interlayer vulnerable regions were identified, and track residual irregularity under the coupling of seismic load and pier settlement were calculated. Through analyzing characteristic parameters such as damage location, damage length, and damage height, the potential causes of abrupt changes in track residual irregularity deformation were explored. Finally, to ensure effective post-earthquake operational safety assessment, wavelet packet transform was employed for time-frequency analysis and feature extraction of residual irregularity signals, and a construction method for characteristic residual irregularity was proposed, enabling irregularity input for post-earthquake train operation simulation. Based on this foundation, an equivalence coefficient of residual irregularity was proposed using the TIC rms index, quantifying the aggravation effect of pier settlement on track residual irregularity. The present work is expected to provide theoretical basis and methodological support for post-earthquake operational safety assessment of high-speed railway. • A damage evolution model was established. • The evolution mechanism and law of track interlayer damage was revealed. • A construction method for characteristic residual irregularity was proposed. • The effect of pier settlement on track residual irregularity was quantified.